1. Field of the Invention
The present invention relates to a device for latching an electrical connection device e.g., an expansion card or a connector to a receiving connector and, more particularly, to a removable shroud type latch that engages ahd surrounds the receiving connector and has engaging portions that removably retain the electrical connection device.
2. Description of Related Art
In expandable electronic devices of today, it is important to maintain various add-on devices and the like, in good electrical contact. This avoids power failures that may hinder proper operation of those devices.
It is common for many different types of single-board electronic systems, such as computers, to have a printed circuit board ("PCB") with a number of soldered connectors in which printed circuit cards or boards, commonly known as "expansion cards," are plugged into at vertical planes with respect to the connectors. However, because of external forces such as shock, vibration, or in the case of cable connector systems, the direct pulling of a cable attached to a connector, the cards are prone to becoming unplugged from the connectors.
One method for preventing the cards from becoming unplugged from the connectors is to increase the normal force of the contact, which in effect increases the retention ability of the connector. However, this method is not practical for a number of reasons. First, the size of the connector may preclude increasing the force of the contact. Second, increasing the contact forces results in increased contact wear. Finally, high forces can create difficulties in plugging and unplugging the card into the connector. To overcome these shortcomings, prior art latching systems provided forces independent from the contact forces, in other words, the latches could be engaged and disengaged independently of the engagement or disengagement of the card to the connector contacts. These latching systems included those used in connection with cable-to-board connectors, in which cables had either plastic or metal latches at their ends which could be squeezed to engage or disengage the connectors. These latching systems, however, could not be used with board-to-board connectors and other similar connector systems.
A common latching device is illustrated by U.S. Pat. No. 3,573,706, entitled "Connector for Mounting a Printed Circuit Board on a Mounting Bar." The '706 patent discloses a connector with a removable "H-shaped" latching spring clip which secures a printed circuit board to a mounting bar. The clip has a first pair of legs which latches the clip to the mounting bar. A second pair of legs extends upwardly from the mounting bar, each leg having a nose with a cammed face which engages the other leg in a hole in the board. However, one drawback of using a device such as this is that when using metal connectors, the metal body of the connector is not also protected from inadvertent electrical contact to other electrically conductive members of a particular assembly. In other words, this structure does nothing to reduce the possibilities of, e.g., electrical short circuits or electrostatic discharge. Furthermore, because the legs which engage the hole on the board cam upwardly at an angle and only contact the board in the hole at some distance from the connector, there is no lead-in for the board. Thus, it can be difficult to blindly mate the board to the connector, which increases the possibility of damaging the connector.
Another conventional latching structure utilizing cammed members with contact pins which engage in a hole of a printed circuit board is disclosed in U.S. Pat. No. 4,373,765, entitled "Plug Connection for Ribbon Cables." The '765 Patent teaches a latching system which is integrated into the connector design. However, a latching system may not be required under all circumstances and conditions. Therefore, a drawback to this system is that it would be very costly to implement these connectors on a PCB to safeguard against situations where it would not be necessary. Furthermore, these latching systems must be fabricated from materials able to withstand high surface mount solder temperatures for when the connector is soldered to the PCB. These materials are generally much more expensive than, e.g., thermoplastic polymers which are unable to withstand these extreme temperatures.
With respect to multiple-board electronic systems, such as mainframes or other high-speed systems, it is common to instead have two-piece connectors because of their greater reliability. However, some of the same concerns regarding board-to-board connectors, namely unplugging, inadvertent electrical contact, and high cost, apply to latching systems for securing two connectors as well. It can thus be generally said that where electrical connectors and connections are concerned, the aforementioned problems exist. Therefore, it would be desirable to have a latch that could alleviate these problems.
With the above considerations in mind, it is an object of the present invention to provide a latch system for positively retaining an electrical connection device to a connector.
It is an object of the present invention to provide a latch for retaining an expansion card to a single-board connector.
It is a further object of the present invention to provide a latch for a single-board connector with a significant lead-in to make blind mating of the connector easier, thus reducing the potential for damaging connectors or other components.
It is a still further object of the present invention to provide a latch system for securing two connectors on a multi-board system.
It is another object of the present invention to provide a latch system which is insulated to protect a metal connecting body from inadvertent electrical contact to other electrically conductive members of an assembly, thereby reducing the possibility of short circuits or electrostatic discharge.
It is yet another object of the present invention to provide a removable shroud latch which can be applied after the soldering process, so that it does not have to be made from a high temperature plastic.